Black screen appears when i turned my laptop

Hi, I have a hp pavilion dv4 series laptop. Recently i am facing a problem with it.When i turn on my laptop a black screen appears. For this i used the method (unpluging the battery, holding the power button for 20 to 30 seconds then reattach the battery and reboot) which was submitted in this forum. And it worked! I thought this problem will never happen again. But after 2 hours when i reboot my laptop the black screen appeared again. Do i have to use that method everytime i log into my laptop? If i hibernate instead of shutting down, will it help? Is there any fixed solution for this?
Please help!!